In the conduct of a number of processes, it is often necessary to agitate liquid reactants themselves or liquid reactants containing a dispersed medium, such as a catalyst in certain chemical reactions, or bacteria and yeast in a fermentation reaction in order to aid mixing and, in some cases, reduce the necessary residence time within the reactor. One convenient method of carrying out such agitation is by sparging the reaction mixture with gas under pressure. In some cases, the gas under pressure enters into the reaction, for example, in a fermentation reaction. Equipment for carrying out such sparged reactions usually consists of a vertically disposed vessel, operated in a batch or continuous manner, with means for introducing a sparging gas at the bottom of the vessel. It passes upwardly through the liquid in the vessel and is then separated at the top of the vessel and discharged. One difficulty with such reactors is that, whether operated batch-wise or continuously, it is necessary to shut down the operation in order to clean or otherwise treat the interior of the reactor. In addition, in some cases, a substantially constant temperature needs to be maintained in the vessel by indirect heat exchange. Where a single vessel of this type is utilized, the limited available heat transfer surface of the vessel makes it difficult to achieve a uniform temperature throughout the vessel. In addition, substantial amounts of energy are necessary to circulate the cooling or heating fluid about the vessel, or through coils disposed within the vessel. For example, in the production of single-cell protein for human and animal consumption, bacteria and yeast are fed to a fermentation vessel with a suitable substrate, such as a hydrocarbon, polysaccharide, alcohol and the like, while oxygen is introduced into the vesse. Such a process is highly exothermic. Since the bacteria or yeast can grow only within a narrow temperature range, the liberated heat needs to be removed continuously and effectively. Conventionally, this is accomplished by circulating cooling fluid through coils in the fermentation vessel and enclosing the vessel with a cooling jacket. Such equipment requires a high pressure pump to circulate the cooling fluid and consequently, a large amount of energy.
It is an object of the present invention to overcome the above and other disadvantages of the prior art. Another object of the present invention is to provide an improved method and apparatus for carrying out a sparged reaction. A further object of the present invention is to provide an improved method and apparatus for carrying out a sparged reaction requiring the addition or removal of heat to the reactor. A still further object of the present invention is to provide an improved method and apparatus for carrying out an exothermic, sparged reaction. Yet another object of the present invention is to provide an improved method and apparatus for carrying out an exothermic sparged reaction with a minimum of energy consumption. Another object of the present invention is to provide a method and apparatus for carrying out a sparged reaction in which heat is added to and/or removed from the reaction vessel at a high rate of efficiency. These and other objects of the present invention will be apparent from the following detailed description when read in conjunction with the drawings.